对于式子x/(x²-1)按照除法的求导计算法则其导函数为[x' *(x²-1) -x *(x²-1)'] /(x²-1)²显然x'=1，(x²-1)'=2x代入得到导数为(x²-1-2x²)/(x²-1)²= -(x²+1)/(x²-1)²
